The session number includes the symbol of the responsible Division or Regional Office. Sessions are identified by three-digit numbers according to the following criteria:

Numbers from 700 to 799 are allocated to Statutory Bodies and their subsidiaries. The numbering of the sessions of the same body is represented by an additional figure separated by a hyphen.

Numbers from 800 to 899 are given to all non-Statutory Body meetings which fall under Categories 1, 2 and 3.

Numbers from 900 to 999 are given to inter-country training courses, workshops, seminars, study tours and other group-training activities. Recurring activities are identified by an additional figure separated by a hyphen.

Numbers from 600 to 699 are given to all other meetings which do not fall into the 700, 800 or 900 series, or into any of the above Categories.